Fans with large diameters require large flow rectifiers. Such large flow rectifiers, whose parts have diameters of 350 mm, especially of more than 500 mm, are expensive: for cost reasons, these parts are usually made of plastic, for example, by means of injection molding. This calls for injection molding tools that entail high tool costs, especially in the case of large parts. Moreover, production by means of plastic injection molding is quite difficult with such large parts, particularly in view of their thin walls. The parts are basically fragile and problematic when it comes to packaging, storage, transportation and handling.
International patent application WO 2014/056657 of the applicant discloses a flow rectifier as well as an axial fan, especially for evaporators in cold-storage rooms. The flow rectifier downstream from the axial fan greatly increases the range of throw of the axial fan, a process in which it converts the swirling outflow of the fan into a uniform axial flow. In this context, the term “range of throw” refers to a distance up to which a limit speed of the air flow is maintained. The flow rectifier is made as a one-piece injection-molded plastic part. Subsequently, it can be detachably mounted as a separate part onto a wall ring or onto a safety grille or support grille of a fan.
Depending on the operating point of the fan, it is advantageous in terms of the throughput rate and the efficiency to use flow rectifiers that have a varying number of baffle vanes, whereby the baffle vanes advantageously have different geometries, depending on the operating point of the fan. As a result, the required production run for a specific flow rectifier is smaller than that of the corresponding fan and thus especially too small for a cost-effective production run, since a separate injection mold is needed for each variant of the flow rectifier.
The documents European patent application EP 1 408 238 A2, U.S. Pat. Nos. 3,883,264, 6,409,472 B1 and Japanese patent specification JP 2012031750 each disclose a flow rectifier for an axial fan, having a hub and at least one vane, whereby the at least one vane can be operatively connected to the hub so as to be detachable. It is also disclosed that the hub forms a cup with a bottom, an inner circumferential wall and an outer circumferential wall, whereby the hub cup has an opening in the hub bottom.
The objective of the invention is to put forward an axial fan with an optional flow rectifier, whereby it should be possible to optimize the geometry of the cost effectively producible flow rectifier for various operating points.
This objective is achieved by an axial fan according to the claims. Advantageous embodiments of the axial fan can be gleaned from the claims.